The mobile phones bring much convenience to the people for long distance communication. As the technology progresses, more and more functions are added to the mobile phones. In addition to the audio communication, functions, such as photography, audio recording, music playing, and video viewing, are all added to list of options of mobile phones. Some of the above functions, such as photography, are so common that they are becoming an integral part of a mobile phone. More and more users are using their mobile phone as a camera. Therefore, improved functions, such as high-pixel pictures and auto-focusing, are considered as essential to the ease of use while posing severe restriction on the thin design of the mobile phone.
The auto-focusing of the mobile phone camera is to control the movement of the camera lens. The current approach to control the focus of the lens in a mobile phone is to use a stepping motor, which increases the manufacturing cost. Therefore, it is important to develop an apparatus for driving the lens of a mobile phone for auto-focusing that can reduce the manufacturing cost.